The challenge of ecological restoration
Recent estimates by the World Conservation Union (IUCN) and World Resources Institute (WRI) suggest that over 2 billion ha of forests are degraded and in need of restoration. Goren Persson, former prime minister of Sweden, proposed the formation of a Global Restoration council to implement the Bonn Challenge to restore 150 million ha of degraded forests by 2020. The importance of forest land cover to climate change mitigation is reflected in international efforts to Reduce Emissions from Deforestation and Degradation (REDD+) of tropical forests, while at the same time enhancing biodiversity and other conservation goals. In accepting the importance of restoring degraded forests, the scientific community must respond with approaches informed by defensible concepts of what defines a forest, what is the threshold between acceptable (because it is somehow natural) disturbance and degradation, and how should current restoration goals be altered to accommodate future climates?